1. Field of the Invention
The present invention relates to a method for winding a coil on an object and a water pump of clutch type provided with the coil. More particularly, the present invention relates to a method for winding more coils on an object having a limited space, and to a water pump of clutch type provided with a coil securing a sufficient operation performance without increasing a size of the water pump of clutch type by using this method.
2. Description of Related Art
Generally, a water pump circulates coolant to an engine and a heater in order to cool the engine and heat a cabin.
The coolant flowing out from the water pump circulates a cylinder block and/or a cylinder head of an engine and cools the engine. In addition, the coolant circulates a heat exchanger and cools an exhaust gas of high temperature. At this time, temperature of the coolant rises, and the heated coolant is used for warming up a cabin of a vehicle. In addition, the heated coolant is cooled at a radiator and flows in the water pump again.
Such a water pump is largely divided into a mechanical water pump and an electric water pump.
The mechanical water pump is connected to a pulley fixed to a crankshaft of the engine and is driven according to a rotation of the crankshaft (i.e., a rotation of the engine). Therefore, coolant amount flowed out from the mechanical water pump is determined according to a rotation speed of the engine.
On the contrary, the electric water pump is driven by a motor controlled by a control apparatus. Therefore, the electric water pump can determines the coolant amount regardless of the rotation speed of the engine. Since components used in the electric water pump, however, is electrically operated, it is important for electrically operated components to have sufficient waterproof performance. If the components have sufficient waterproof performance, performance and durability of the electric water pump may also improve. In addition, the electric water pump has more components (a stator, a rotor, a water-proof means, and so on) than the mechanical water pump. So, manufacturing cost of the electric water pump is expensive and it is difficult to manufacture the electric water pump.
Recently, a mechanical water pump (e.g., water pump of clutch type) which selectively pressurizes the coolant according to a driving condition of the engine and supplies it to the engine has been developed. According to such a water pump of clutch type, a pulley is selectively connected to a shaft according to the driving condition of the engine, and the selectively connection of the pulley and the shaft is achieved by magnetic force generated by a coil wound on a coil case.
Hereinafter, a conventional method for winding a coil on a coil case of a water pump of clutch type will be described.
FIG. 4 is a cross-sectional view of a conventional coil, and FIG. 5 is an enlarged view of FIG. 4.
As shown in FIG. 4 and FIG. 5, coil layers 210 are wound on a coil case according to a conventional art. A coil 212 in the coil layers 210 is wound so as to form a plurality of rows. At this time, the coil 212 is wound as a rhombohedral packing. That is, cross-sectional centers of a plurality of coils forming a m-th row and a (m+1)-th row are arranged to form a zigzag shape, and an angle θ between the cross-sectional centers of the two neighboring coils forming the m-th row and one cross-sectional center of the coil forming the (m+1)-th row and contacting with the cross-sectional centers of the two neighboring coils is 60°. However, a pore 216 is formed among three neighboring coils 212 among a rhombohedral packing. Formation of the pore 216 restricts numbers of coils wound on the coil case.
Generally, magnetic force generated by the coil 212 is proportional to the numbers of coils 212 wound on the coil case. Therefore, it is very important for improving operation performance of a water pump of clutch type to wind more coils 212 on the coil case having a limited space.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.